title: Solvation forces between silica bodies in supercritical carbon dioxide.
abstract: We report Monte Carlo simulations of the solvation pressure between two planar surfaces, which represent the interface of spherical silica nanoparticles in supercritical carbon dioxide. Carbon dioxide (CO2) was modeled as an atomistic dumbbell or a spherical Lennard-Jones particle. The interaction between CO2 molecules and silica surfaces was characterized by the standard Steele potential with energetic heterogeneities representing the hydrogen bonds. The parameters for the solid-fluid interaction potentials were obtained by fitting our simulations to the experimental isotherms of CO2 sorption on mesoporous siliceous materials. We studied the dependence of the solvation force on the distance between planar silica surfaces at T = 318 K, at equilibrium bulk pressures p(bulk) ranging from 69 to 200 atm. At 69 atm, we observed a long-range attraction between the two surfaces, and it vanished when the pressure was increased to 102 and then 200 atm. The results obtained with different fluid models were consistent with each other. According to our observations, energetic heterogeneities of the surface have negligible influence on the solvation pressure. Using the Derjaguin approximation, we calculated the solvation forces between spherical silica nanoparticles in supercritical CO2 from the solvation pressures between the planar surfaces.
authors.affiliation: Department of Chemical and Biochemical Engineering, Rutgers, the State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854, USA.
authors.forename: Aleksey
authors.initials: A
authors.lastname: Vishnyakov
authors.forename: Yangyang
authors.initials: Y
authors.lastname: Shen
authors.forename: M Silvina
authors.initials: MS
authors.lastname: Tomassone
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D006860:Hydrogen Bonding; D009010:Monte Carlo Method; D053758:Nanoparticles / Q000737:chemistry; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013499:Surface Properties
chemical_list: D012997:Solvents; D002245:Carbon Dioxide; D012822:Silicon Dioxide